title: Analysis of gabapentin in equine plasma with measurement uncertainty estimation by liquid chromatography-tandem mass spectrometry.
abstract: Gabapentin (GPT) is an antiepileptic drug that was approved in 1993 for use in the management of neurotrophic pain and as an adjunctive therapy for refractory partial seizure in humans. It is also being tested in veterinary medicine as an adjunctive medication in the treatment of pain due to laminitis, neuropathic, or chronic pain. Gabapentin is readily available by prescription and even on the internet; therefore, it has the potential of being used in racehorses to mask pain. It is for this reason that a sensitive liquid chromatography-tandem mass spectrometry method has now been developed for the analysis of GPT in equine plasma and for studying the pharmacokinetic and pharmacodynamic profiles of GPT in the horse. Sample preparation was by rapid protein precipitation with acetonitrile. Analyte separation was achieved on a reversed-phase ACE C(18) column and analyzed by a hybrid triple-quadrupole linear ion trap mass spectrometer in positive electrospray ionization mode. Limits of detection, quantification, and confirmation of GPT were 1, 10, and 20 ng/mL, respectively. Calibration curve showed excellent linearity within the 10-2500 ng/mL range (r(2) > 0.999). Intra- and interday precision defined by coefficient of variation was <10%. Intra- and interday accuracy (bias %) was within 90-110%. Measurement uncertainty estimation was 8.6%. The method has been successfully used in the analysis of GPT in equine plasma following its administration to research horses for pharmacokinetic studies and in routine forensic analysis for doping control in racehorses in the State of Pennsylvania.
authors.affiliation: University of Pennsylvania, School of Veterinary Medicine, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Cornelius E
authors.initials: CE
authors.lastname: Uboh
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Soma
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Li
authors.forename: Fuyu
authors.initials: F
authors.lastname: Guan
authors.forename: Youwen
authors.initials: Y
authors.lastname: You
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Rudy
authors.forename: Jin-Wen
authors.initials: JW
authors.lastname: Chen
mesh_terms: D000588:Amines / Q000097:blood* / Q000737:chemistry; D000818:Animals; D000927:Anticonvulsants / Q000097:blood* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000662:veterinary; D003509:Cyclohexanecarboxylic Acids / Q000097:blood* / Q000737:chemistry; D000077206:Gabapentin; D006736:Horses / Q000097:blood*; D010316:Particle Size; D053719:Tandem Mass Spectrometry / Q000662:veterinary; D005680:gamma-Aminobutyric Acid / Q000097:blood* / Q000737:chemistry
chemical_list: D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin